02139nas a2200217   4500008004100000022001400041245012400055210006900179260007500248300001200323490000700335520131900342653002201661653001701683653001701700653001301717653002101730100002401751700002501775856012101800       2007                        eng d  a1053-050900aFluorescence quenching and time-resolved fluorescence studies of alpha-Mannosidase from Aspergillus fischeri (NCIM 508)0 aFluorescence quenching and timeresolved fluorescence studies of   a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGER/PLENUM PUBLISHERScNOV  a599-6050 v173 a<p>Apart from the vital role in glycoprotein biosynthesis and degradation, alpha-mannosidase is currently an important therapeutic target for the development of anticancer agents. Fluorescence quenching and time-resolved fluorescence of alpha-mannosidase, a multitryptophan protein from Aspergillus fischeri were carried out to investigate the tryptophan environment. The tryptophans were found to be differentially exposed to the solvent and were not fully accessible to the neutral quencher indicating heterogeneity in the environment. Quenching of the fluorescence by acrylamide was collisional. Surface tryptophans were found to have predominantly positively charged amino acids around them and differentially accessible to the ionic quenchers. Denaturation led to more exposure of tryptophans to the solvent and consequently in the significant increase in quenching with all the quenchers. The native enzyme showed two different lifetimes, tau (1) (1.51 ns) and tau (2) (5.99 ns). The average lifetime of the native protein (tau) (3.187 ns) was not affected much after denaturation (tau) (3.219 ns), while average lifetime of the quenched protein samples was drastically reduced (1.995 ns for acrylamide and 1.537 ns for iodide). This is an attempt towards the conformational studies of alpha-mannosidase.</p>10aalpha-Mannosidase10aDenaturation10afluorescence10alifetime10aSolute quenching1 aShashidhara, K., S.1 aGaikwad, Sushama, M.  uhttps://library.ncl.res.in/content/fluorescence-quenching-and-time-resolved-fluorescence-studies-alpha-mannosidase-002108nas a2200277   4500008004100000022001400041245011500055210006900170260007500239300001200314490000700326520110400333653002001437653001701457653001701474653002601491653002401517100002401541700002501565700001901590700001801609700002601627700002001653700002701673856013001700       2009                        eng d  a1053-050900aComparative studies of two araceous lectins by steady state and time-resolved fluorescence and CD spectroscopy0 aComparative studies of two araceous lectins by steady state and   a233 SPRING ST, NEW YORK, NY 10013 USAbSPRINGER/PLENUM PUBLISHERScMAR  a239-2480 v193 a<p>Transitions in the tryptophan microenvironment and secondary structure of two monocot lectins from Sauromatum guttatum and Arisaema tortuosum under different denaturing conditions were studied by steady state and time resolved fluorescence and CD spectroscopy. The lectins exist as tetramers with a single tryptophan residue estimated per monomer, present in a polar environment. Quenching with ionic quenchers showed predominantly electropositive environment for tryptophan residues. Acrylamide had maximum quenching effect. A decrease in KI quenching due to lectin denaturation indicated redistribution of charges as a result of possible conformational change. The two values for lifetimes of tryptophanyl population (1.2-1.4 and 6.3-6.4 ns) reduced substantially on quenching or denaturation. Similarly, both the lectins showed a drastic loss of secondary structure in 5 M Gdn-HCl or 6 M Urea or at pH 2.0 and below. For the first time araceous lectins, like legume lectins are shown to bind adenine. The presence of a compact structure at alkaline pH 10.0-12.0 was observed in CD spectra.</p>10aAraceae lectins10aDenaturation10afluorescence10aLifetime spectroscopy10aSecondary structure1 aDharker, Poorva, N.1 aGaikwad, Sushama, M.1 aSuresh, C., G.1 aDhuna, Vikram1 aKhan, Mohammad, Islam1 aSingh, Jatinder1 aKamboj, Sukhdev, Singh  uhttps://library.ncl.res.in/content/comparative-studies-two-araceous-lectins-steady-state-and-time-resolved-fluorescence-and-0